The present invention relates to an image forming apparatus for forming an image in accordance with image information from an original placed on an exposure table.
As shown in FIG. 1, an image forming apparatus of this type is provided with an optical unit 3 which illuminates an original placed on an exposure table 1 to scan the same, and directs reflected light from the original to a photosensitive drum 2. The optical unit 3 includes a lamp 4 moving along the exposure table 1 to illuminate the original, and mirrors 5 and 6 and a lens unit 7 for directing the reflected light from the original to the photosensitive drum 2.
The optical unit 3 is provided with a fan 8 for discharging air in the unit 3 to the outside of the apparatus in order to prevent the temperature inside the unit 3 from being increased by heat from the lamp 4. Meanwhile, a relatively wide space is defined inside the optical unit 3 to allow the lamp 4 and the mirrors 5 to move along the exposure table 1.
In the prior art image forming apparatus, the fan 8 is located at one side portion of a housing 9 of the apparatus, underlying the optical unit 3. The fan 8 used the prior case is a line-flow fan. However, the space for the optical unit 8 is too wide to be ventilated efficiently. In other words, it is impossible to effectively discharge air from the optical unit 8 and introduce fresh air from the outside into the unit 8. Unavoidably, therefore, the efficiency of cooling the interior of the optical unit 3 is low.